The present invention concerns an inlet manifold arrangement for an internal combustion engine.
The inlet manifold of an internal combustion engine, as is known, conveys the air of combustion to the engine cylinders as uniformly as possible. It is frequently desirable to use the same engine design for different types of engine, for example for a normally aspirated engine or for a turbocharged engine. However, in known engines, converting a normally aspirated engine to a turbocharged engine requires extensive modifications to the inlet manifold for adding a charging air cooler thereto for connecting a turbocharger compress the air of combustion for the engine. This compression of the air of combustion is not used effectively to increase the engine power. Compressing the air of combustion increases the amount of such air fed to the engine per cycle and. Consequently more fuel can be fed to the engine and burned. The compression of the air of combustion increases its temperature, which, as is known, causes the air to attempt to expand. To counteract the above disadvantage, i.e. warming of the compressed air, it is known to allow the compressed air of combustion to pass through a charging air cooler before the air is fed to the engine. Conventionally, such a charging air cooler is a separate unit that is connected to the engine, which usually consists of a core disposed in a casing. The coolant for the core, usually the engine coolant, flows through the casing, thereby cooling the air of combustion which passes through the core.
This type of charging air cooler is associated with a number of serious disadvantages.
One disadvantage is that it is difficult to detect whether coolant is escaping into the air of combustion.
Another disadvantage is that it is awkward to dimension the cooler, or radiator, for different types of internal combustion engines, each having different other performance levels in such situations a new casing has to be designed and built.
WO-83/02481 discloses a heat exchanger for cooling or pre-heating the air of combustion for a turbocharged internal combustion engine. The heat exchanger consists of a self-contained system comprising an element equipped with a heat-storing active medium which is connected in a heat-exchanging manner to the air of combustion. The element is usually filled with a heat-accumulating active medium, which acts as a latent accumulator at the engine operating temperature. The medium changes phase from solid to liquid when the engine power output is high and when the charging air has to be cooled. At idling or low-load, the medium changes phase in the opposite direction and heats the intake air. To connect a charging air cooler in this way, it is conventional to use the ambient air as a cooling medium or a heat-accumulating medium.
U.S. Pat. No. 4,269,158 discloses a charging air cooler for a turbocharged internal combustion engine, which cooler is to be used with the engine inlet manifold the inlet manifold is constructed such that it can be used with or without the charging air cooler. The cooler is mounted, like manner to a spacer element, between the cylinder head and the inlet manifold.